Benefit Plans and Other Postretirement Benefits, Weighted-average assumptions (Details) - Pension Benefits - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
U.S.
Weighted-average assumptions used to determine benefit obligations
Benefit obligation discount rate (as a percent)	3.48%	3.93%
Increase (decrease) in benefit obligation due to change in discount rate	$ 24.0
International Plans
Weighted-average assumptions used to determine benefit obligations
Benefit obligation discount rate (as a percent)	2.21%	2.28%